1. Field of the Invention
This invention relates generally to cancer treatment and more specifically, to cancer treatments which selectively induce apoptosis in cancer cells.
2. Description of Related Art
Cancer was generally treated with combinations of surgery, chemotherapy and radiation with varying degrees of success. One way cancer has been targeted for treatment is that cancer cells tend to be rapidly dividing cells. Thus, current chemotherapeutic approaches target rapidly dividing tumor cells. This approach is generally ineffective when the cancer is dormant or slow growing. These types of treatments also impact other, noncancerous cells that divide rapidly, causing harmful side effects.
These harmful side effects, however, are not present in treatments that induce apoptosis in the cancer cells. Apoptosis is also called "programmed cell death" or "cell suicide." (Krammer, et al., "Apoptosis in the APO-1 System", Apoptosis: The molecular Basis of Cell Death, pp. 87-99 Cold Spring Harbor Laboratory Press, 1991). In contrast to the cell death caused by cell injury, apoptosis is an active process of gene-directed, cellular self-destruction. Apoptosis serves a biologically meaningful function. (Kerr, J. F. R. and J. Searle, J. Pathol. 107:41, 1971).
One of the examples of the biologically meaningful functions of apoptosis is the morphogenesis of an embryo. (Michaelson, J., Biol. Rev. 62:115, 1987). Just like creating a sculpture, clay is added, and clay is removed; organ formation (morphogenesis) of an embryo relies on cell growth (addition of clay) as well as cell death (removal of clay). As a matter of fact, apoptosis plays a key role in the human body from the early stages of embryonic development through to the inevitable decline associated with old age. (Wyllie, A. H., Int. Rev. Cytol. 68:251, 1980).
The normal function of the immune, gastrointestinal and hematopoietic system relies on the normal function of apoptosis. When the normal function of apoptosis goes awry, the result can be any of the following diseases: cancer, viral infections, autoimmune disease/allergies, neurodegeneration or cardiovascular diseases.
The idea that cancer may be caused by insufficient apoptosis emerged only recently (Cope, F. O. and Wille, J. J., "Apoptosis": The Molecular Basis of Cell Death, Cold Spring Harbor Laboratory Press, p. 61, 1991). This idea opens a door for a new concept in cancer therapy--cancer cells may be killed by encouraging apoptosis. Apoptosis modulation, based on the processes present in normal development, is a potential mechanism for controlling the growth of tumor cells. Restoring apoptosis in tumor cells is an attractive approach because it programs the cancer cells to commit suicide.
Thus, the cancer cells can be killed without killing the host. The success of this treatment, however, is dependent upon the availability of drugs that can selectively induce apoptosis in tumor cells without affecting normal cells.
From the preceding descriptions, it is apparent that the compositions and methods currently being used have significant disadvantages. Thus, important aspects of the technology used in the field of invention remain amenable to useful refinement.